src/mscorlib/shared/System/IO/StreamHelpers.CopyValidation.cs


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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

namespace System.IO
{
    /// <summary>Provides methods to help in the implementation of Stream-derived types.</summary>
    internal static partial class StreamHelpers
    {
        /// <summary>Validate the arguments to CopyTo, as would Stream.CopyTo.</summary>
        public static void ValidateCopyToArgs(Stream source, Stream destination, int bufferSize)
        {
            if (destination == null)
            {
                throw new ArgumentNullException(nameof(destination));
            }

            if (bufferSize <= 0)
            {
                throw new ArgumentOutOfRangeException(nameof(bufferSize), bufferSize, SR.ArgumentOutOfRange_NeedPosNum);
            }

            bool sourceCanRead = source.CanRead;
            if (!sourceCanRead && !source.CanWrite)
            {
                throw new ObjectDisposedException(null, SR.ObjectDisposed_StreamClosed);
            }

            bool destinationCanWrite = destination.CanWrite;
            if (!destinationCanWrite && !destination.CanRead)
            {
                throw new ObjectDisposedException(nameof(destination), SR.ObjectDisposed_StreamClosed);
            }

            if (!sourceCanRead)
            {
                throw new NotSupportedException(SR.NotSupported_UnreadableStream);
            }

            if (!destinationCanWrite)
            {
                throw new NotSupportedException(SR.NotSupported_UnwritableStream);
            }
        }
    }
}